net: mpc8xx_fec: ensure mdiodev->name is NULL terminated after MDIO_NAME_LEN truncation

strncpy() simply bails out when copying a source string whose size
exceeds the destination string size, potentially leaving the destination
string unterminated.

One possible way to address is to pass MDIO_NAME_LEN - 1 and a
previously zero-initialized destination string, but this is more
difficult to maintain.

The chosen alternative is to use strlcpy(), which properly limits the
copy len in the (srclen >= size) case to "size - 1", and which is also
more efficient than the strncpy() byte-by-byte implementation by using
memcpy. The destination string returned by strlcpy() is always NULL
terminated.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Ramon Fried <rfried.dev@gmail.com>

diff --git a/drivers/net/mpc8xx_fec.c b/drivers/net/mpc8xx_fec.c
index 282c2599d3c48ab47b3595ab545c70c49a47a2d8..4eb826028111c47d2038246e26d649165e111182 100644 (file)
--- a/drivers/net/mpc8xx_fec.c
+++ b/drivers/net/mpc8xx_fec.c
@@ -160,7 +160,7 @@ int fec_initialize(struct bd_info *bis)
                struct mii_dev *mdiodev = mdio_alloc();
                if (!mdiodev)
                        return -ENOMEM;
-               strncpy(mdiodev->name, dev->name, MDIO_NAME_LEN);
+               strlcpy(mdiodev->name, dev->name, MDIO_NAME_LEN);
                mdiodev->read = fec8xx_miiphy_read;
                mdiodev->write = fec8xx_miiphy_write;